/**
 * Project Name:alqframework
 * File Name:IdWorker.java
 * Package Name:org.alqframework.snowflake
 * Date:2016年9月7日下午5:47:44
 * Copyright (c) 2016, chenzhou1025@126.com All Rights Reserved.
 *
*/

package com.alqsoft.util;
/**
 * ClassName:IdWorker <br/>
 * Function: TODO ADD FUNCTION. <br/>
 * Reason:	 TODO ADD REASON. <br/>
 * Date:     2016年9月7日 下午5:47:44 <br/>
 * @author   张灿
 * @version  
 * @since    JDK 1.8
 * @see 	 
 */
public class IdWorker {
    private final long workerId;
    private final static long twepoch = 1361753741828L;
    private long sequence = 0L;
    private final static long workerIdBits = 4L;
    public final static long maxWorkerId = -1L ^ -1L << workerIdBits;
    private final static long sequenceBits = 10L;
 
    private final static long workerIdShift = sequenceBits;
    private final static long timestampLeftShift = sequenceBits + workerIdBits;
    public final static long sequenceMask = -1L ^ -1L << sequenceBits;
 
    private long lastTimestamp = -1L;
 
    public IdWorker(final long workerId) {
        super();
        if (workerId > this.maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format(
                    "worker Id can't be greater than %d or less than 0",
                    this.maxWorkerId));
        }
        this.workerId = workerId;
    }
 
    public synchronized long nextId() {
        long timestamp = this.timeGen();
        if (this.lastTimestamp == timestamp) {
            this.sequence = (this.sequence + 1) & this.sequenceMask;
            if (this.sequence == 0) {
                System.out.println("###########" + sequenceMask);
                timestamp = this.tilNextMillis(this.lastTimestamp);
            }
        } else {
            this.sequence = 0;
        }
        if (timestamp < this.lastTimestamp) {
            try {
                throw new Exception(
                        String.format(
                                "Clock moved backwards.  Refusing to generate id for %d milliseconds",
                                this.lastTimestamp - timestamp));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
 
        this.lastTimestamp = timestamp;
        long nextId = ((timestamp - twepoch << timestampLeftShift))
                | (this.workerId << this.workerIdShift) | (this.sequence);
      System.out.println("timestamp:" + timestamp + ",timestampLeftShift:"
              + timestampLeftShift + ",nextId:" + nextId + ",workerId:"
              + workerId + ",sequence:" + sequence);
        return nextId;
    }
 
    private long tilNextMillis(final long lastTimestamp) {
        long timestamp = this.timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = this.timeGen();
        }
        return timestamp;
    }
 
    private long timeGen() {
        return System.currentTimeMillis();
    }
     
     
    public static void main(String[] args){
        IdWorker worker2 = new IdWorker(2);
        for (int i = 0; i < 10000; i++) {
        	System.out.println(worker2.nextId());
		}
    }
 
}
